Exhaust gas oxygen sensors are sometimes equipped with an integral heating element that is electrically activated following engine starting to quickly bring the oxygen sensor to a desired operating temperature such as 700° C. This minimizes the interval of open-loop fuel control following a cold engine start, and maintains a predictable relationship between the oxygen sensor output signal and the exhaust gas equivalence or air/fuel ratio. In cases where the heating element is in close proximity to the oxygen sensor, the temperature of the oxygen sensor can be inferred from the resistance of the heating element. However, the heater includes conductor leads in addition to the heating element, and the resistance of the conductor leads can vary significantly due to part-to-part variability and variations in operating temperature. As a result, it can be difficult to reliably maintain the oxygen sensor at the desired operating temperature.